Corn knife sharpener



May 9, 1967 Filed Sept. 8, 1964 C. E. LECKINGTON CORN KNIFE SHARPENER 2Sheets-Sheet 1 I B fi 7 fi QM INVENTOR. K CHARLES E. LECKINGTON orneyUnited States Patent 3,318,050 CORN KNIFE SHARPENER Charles E.Leckington, 1530 Springhill Road, Albany, Greg. 97321 Filed Sept. 8,1964, Ser. No. 394,661 7 Claims. (Cl. 51-96) This invention relates to amachine for sharpening the knives used for removing kernels of corn fromthe cob.

Such knives are of complex shape having curved blades with bevelledhelical cutting edges so that a plurality of the knives may be arrangedto form a circular opening. When the circle of knives is rotated andears of corn are moved through the opening one after another, thekernels are cut off the cobs.

Previous machines for sharpening the knives have been extremelycomplicated and expensive and so the knives are usually sharpened byhand on an ordinary abrasive wheel. This is a tedious process requiringconsiderable skill in order to achieve uniformity and accuracy and avoidexcessive removal of metal.

The general object of the present invention is, therefore, to provide arelatively simple and inexpensive machine for sharpening corn knivesuniformly and accurately, to provide a machine which will hone theknives faster while at the same time avoiding excessive loss of metaland burning of the blades and to provide a machine of the type describedwhich requires relatively little skill to operate.

The present machine employs a new and improved knife holder for holdingthe knife at an oblique angle to an abrasive wheel and imparting arotary motion to the knife during the honing operation. The knife holderis mounted on a combination of slides to adjust the position of theknife relative to the wheel in two different directions. A dressing toolis also included to keep the working surface on the wheel in truecylindrical shape.

The invention will be better understood and the foregoing and additionalobjects and advantages will become apparent from the followingdescription of the preferred embodiment of the invention illustrated onthe accompanying drawings. Various changes may be made, however, in thedetails of construction and arrangement of parts and certain featuresmay be employed without others. All such modifications within the scopeof the appended claims are included in the invention.

In the drawings:

FIGURE 1 is a top plan view of the machine;

FIGURE 2 is a front elevation view;

FIGURE 3 is a view taken on the line 3--3 of FIG- URE 1;

FIGURE 4 is a view taken on the line 44 of FIG- URE l FIGURE 5 is a viewshowing the convex side of the knife blade;

FIGURE 6 is a view showing the concave side of the knife blade; and

FIGURE 7 is a view taken on the line 7-7 of FIG- URE 6.

The machine comprises a base plate 10 having a horizontal bearing 11 fora circular abrasive wheel 12 which is driven at slow speed by beltpulley 13. The wheel has a cylindrical Working surface 14 of very finetexture for honing rather than grinding.

Mounted on the base is a guideway 15 for a lower slide 16. The slide ismovable toward and away from the wheel in a direction parallel with thewheel axis by hand wheel 17 fixed on a threaded shaft 18. Longitudinalmovement of the shaft is prevented by a thrust bearing 19 on base 10.The slide carries a nut 20 engaged with the threads on shaft 18.

Lower slide 16 carries a guideway for an upper slide 26 which movestoward and away from. the wheel in a direction transverse to the wheelaxis. Slide 26 is freely movable by hand but its movement toward thewheel is limited by an abutment 27 on guide 25 which engages a stopscrew 28 having threaded engagement with an apertured bracket 29 on theslide 26.

A support 30 is pivotally mounted on upper slide 26 by a single screw 31as shown in FIGURE 3. Angular adjustment is maintained by a pair ofsetscrews 32 in bracket ears 33 on the slide on opposite sides of pivotscrew 31. Support 34 carries an inclined bean'ng housing 35 whichprovides rotatable support for the knife holder 36.

The knife holder has a journal portion 35a rotatably mounted in a pairof hearings in the bearing housing 35. Mounted on this journal are aflat table portion 37 and an axial cylindrical extension 38 having onone side there of a knife blade positioning block 39 as shown in FIG-URE 3. Plate 37 is equipped with a stud 40 and a leaftype clamp spring41 to hold the knife K. In sharpening a knife, the knife holder isrotated back and forth on the axis of journal 35a while the bladeportion of the knife is pressed against the wheel by block 39 at acontact point C on one side of the wheel.

As shown in FIGURE 4, the under side of plate 37 is equipped with adepending lug 45 which projects between two ears 46 on the bearinghousing 35. Stop screws 47 in these ears are adjustable to limit theangle of rotation of the knife holder.

As best shown in FIGURES 1 and 3, the upper slide 26 also has aprojecting stud 50 carrying a dressing tool 51 to true the cylindricalworking surface of the wheel 12. This tool is removed or turned to aninoperative position while knives are being sharpened.

It will be observed in FIGURE 2 that the rotational axis A of the knifeholder 36 is inclined at a fixed angle as indicated at X with respect tothe horizontal line H which is parallel with the wheel axis. Further, asindicated at Y in FIGURE 1, the axis A is seen to be disposed at a smallangle later-ally from the line P which is parallel with the axis of thewheel. Angle Y is adjustable by setscrews 32. Thus, the axis A of theknife holder is inclined from the horizontal and it is also turnedlaterally slightly out of parallelism with a vertical plane through theaxis of the wheel. The direction of axis A may also he describedgenerally as oblique to all planes which contain the wheel axis. Thereasons for these angles will be explained in relation to the shape ofthe knife K as illustrated in FIGURES 5 to 7.

Referring back to FIGURES l and 3, it will be seen that the knife has aflat base portion with a circular hole 61 and an arcuate end 62containing a notch 63. This hole and notch are provided for accuratelypositioning the knife in a convention-a1 corn cutting machine. As seenin FIGURES 5 to 7, there is an upstanding blade portion 64 at theopposite end of base portion 60 having a helical cutting edge 65. Forpurposes of identification in FIG- URE 7, the low end of cutting edge 65is indicated at 66 and the high end at 67.

This blade portion has a concave side 70in FIGURE 6 having a radiusapproximating the radius of a corn cob and a convex back side 71 shownin FIGURE 5. The

upper or outer end of the blade has a concave cylindrical bevel 72 onits concave side which intersects surface 70 on a sloping line 73. Theconvex back surface 71 is a cylindrical surface produced by honing,which surface is parallel to the inside cylindrical surface 7d. Thesurface 71 inter-sects the bevelled surface 72 on an inclined andslightly concave helical line which forms the cutting edge 65. Thisconfiguration of the cutting edge must be maintained in order to makethe knife operate satisfactorily and considerable skill and care arerequired in sharpening such knives by hand.

The desired helix angle X in FIGURE 6 is maintained by inclining therotational axis of the knife holder from the horizontal as indicated bythe angle X in FIGURE 2. It is also desired to maintain the cylindricalhoned back surface 71 at a small angle from a perpendicular with respectto base port-ion 60. This is represented by the angle Y in FIGURE 7Where the line 80 is perpendicular to base 60. This is accomplished byturning bearing housing 35 on mounting screw 31 to a similar angle onslide 26 with respect to a vertical plane through the axis of the honingwheel as indicated by the angle Y in FIGURE 1.

Stated in more general terms without reference to horizontal andvertical directions in the preferred embodiment, the axis A of the knifeholder is inclined from a direction radial to the wheel at the contactpoint C by an angle corresponding to the complement of the angle Y ofthe knife blade in FIGURE 7 and is inclined from a direction tangentialto the contact point at an angle corresponding to the complement of thehelix angle X in FIGURE 6.

In operation, the flat base 60 of the knife K is placed on table 37 withlocating stud 40 in the hole 61. Then the knife is turned on the stud toengage its base under spring finger 41 and bring the concave surface 70of upstanding cutting blade against locating block 39, as best shown inFIGURES l and 3. Lower slide 16 is adjusted to cause surface 71 toextend across the cylindrical working surface 14 of the wheel. Then thestop screw 28 is adjusted so that only the necessary amount of metalwill be removed from surface 71 when upper slide 26 is moved to- Wardthe wheel. Setscrews 32 are adjusted as described. Once theseadjustments have been made for a single knife, they do not have to bealtered for sharpening the rest of the knives of the set.

Upper slide 26 is advanced toward the wheel as table 37 is grasped androtated back and forth through the angle permitted by stop screws 47.Locating block 39 then operates as a pressure member to press thesurface 71 against the wheel and prevent deflection of the blade. Metalwill be removed from the surface 71 until stop screw 28 engages abutment27 whereupon the sharpening operation is completed and the blade may beremoved and replaced by another blade of the set. In replacing theblades on table 37, the slide 26 is retracted forward to provide a widespace between block 39 and the wheel.

In a corn cutting machine, a plurality of the knives K are mounted on arotating annular plate or flange with the blade portions 64 extendingaxially and forming a stepped circle of cutting edges 65. As ears ofcorn are fed axially into this circle, the kernels are cut off and thecob passes on through. When the knives become dull, the whole set mustbe sharpened. When the first knife has been placed in the sharpeningmachine and the adjustments made at 17, 28 and 32 as described, theknives of the set may be sharpened one after another in rapid successionwithout any further adjustment.

This assures that all the knives will be identical, with the propershape of cutting edge, and that the operator will not hone some of theknives more than others. Stop screw 28 limits the honing on every knifeat the same point. Each knife is assured of being at proper position inthe knife holder because the blade portion 64 bears directly against thepositioning block 39. Block 39 and stud 40 hold the knife in the sameposition relative to axis A that the knife occupies in relation to theaxis of the rotary knife holder in the corn cutting machine. Thus, therather delicate sharpening operation may be performed accurately andquickly without burning and without requiring great skill on the part ofthe operator.

Having now described my invention and in what manner the same may beused, what I claim as new and desire to protect by Letters Patent is:

l. A corn knife sharpening machine comprising a honing wheel mounted forrotation on a horizontal axis and having a cylindrical working surface,a horizontal slide movable transversely of said axis toward and awayfrom said wheel, a knife holder mounted for rotational movement on saidslide about an axis which is inclined vertically from horizontal andinclined laterally toward said wheel axis, means for clamping a knife onsaid holder, and a positioning block on said holder arranged to engage aportion of the knife blade directly behind the blade surface to beground and press said blade surface against said wheel surface when saidslide is moved toward said wheel.

2. A corn knife sharpening machine comprising a base plate, a honingwheel mounted on said base plate for rotation on a horizontal axis andhaving a cylindrical working surface, a horizontal slide on said baseplate movable longitudinally of said axis toward and away from saidwheel, a horizontal slide mounted on said first slide for movementtransversely of said wheel axis toward and away from said wheel, a knifeholder mounted on said last slide to present a knife blade to apredetermined point of contact on said working surface on one side ofsaid wheel, said knife holder being mounted for rotation on an axiswhich is inclined vertically from horizontal and inclined laterallytoward said wheel axis, and means for clamping a knife on said holder.

3. A machine as defined in claim 2, including a dressing tool for thehoning wheel mounted on said last slide.

4. A machine for sharpening a corn knife having a fiat base portion witha cylindrically curved blade portion outstanding from said base portionat a small angle from perpendicular to said base portion, said bladeportion having a helical cutting edge at a predetermined helix anglerelative to said base portion; said machine comprising a honing wheelhaving a cylindrical working surface, a knife holder arranged to presentsaid blade portion to a predetermined point of contact on said workingsurface, said knife holder being mounted for rotation on an axis ofrotation inclined from a direction radial to the wheel at said point ofcontact at an angle corresponding to the complement of said small angleof said knife blade and inclined from a direction tangentialto saidpoint of contact at an angle corresponding to the complement of saidhelix angle.

5. A machine for sharpening a corn knife having a flat base portion witha cylindrically curved blade portion outstanding from said base portionat a small angle from perpendicular to said base portion, said bladeportion having a helical cutting edge at a predetermined helix anglerelative to said base portion; said machine com prising base plate, ahoning wheel mounted on said base plate for rotation on a horizontalaxis and having a cylindrical working surface, a horizontal slidemounted on said base plate for movement toward and away from said wheelin a direction parallel with the axis of the wheel, a horizontal slidemounted on said first slide for movement toward and away from the wheelin a direction transversely of said wheel axis, a knife holder mountedon said last slide and arranged to present said blade portion to apredetermined point of contact on said working surface, said knifeholder being mounted for rotation on an axis inclined from horizontal atan angle corresponding to said helix angle and inclined laterally towardsaid wheel axis at an angle corresponding to said small angle.

6. A corn knife sharpening machine as defined in claim 1, said knifeholder comprising a supporting hearing on said inclined axis, a journalmounted for rotation in said bearing, a flat table plate on said journalextending perpendicular to said inclined axis, a knife locating stud onsaid plate, said means for clamping a knife on said holder comprising aspring finger for clamping the knife against said plate, saidpositioning block being mounted on said plate at a distance from saidinclined axis for pressing an upstanding blade portion of the knifeagainst said honing wheel.

7. In a machine as defined in claim 6, a pivotally mounted support forsaid bearing, and setscrews engaging said support at a distance from thepivotal axis of said support to adjust the angular position of saidsupport.

References Cited by the Examiner UNITED STATES PATENTS 10 ROBERT c.RIORDON, Primary Examiner.

D. G. KELLY, Assistant Examiner.

1. A CORN KNIFE SHARPENING MACHINE COMPRISING A HONING WHEEL MOUNTED FORROTATION ON A HORIZONTAL AXIS AND HAVING A CYLINDRICAL WORKING SURFACE,A HORIZONTAL SLIDE MOVABLE TRANSVERSELY OF SAID AXIS TOWARD AND AWAYFROM SAID WHEEL, A KNIFE HOLDER MOUNTED FOR ROTATIONAL MOVEMENT ON SAIDSLIDE ABOUT AN AXIS WHICH IS INCLINED VERTICALLY FROM HORIZONTAL ANDINCLINED LATERALLY TOWARD SAID WHEEL AXIS, MEANS FOR CLAMPING A KNIFE ONSAID HOLDER, AND A POSITIONING BLOCK ON SAID HOLDER ARRANGED TO ENGAGE APORTION OF THE KNIFE BLADE DIRECTLY BEHIND THE BLADE SURFACE TO BEGROUND AND PRESS SAID BLADE SURFACE AGAINST SAID WHEEL SURFACE WHEN SAIDSLIDE IS MOVED TOWARD SAID WHEEL.